Figure 9.27.
The screenshot illustrates the Gradients dialog
The Gradients dialog offers a gradient palette which is used to select a
gradient -- a set of colors arranged in a linear scale -- for use with
the Blend tool and numerous other
operations. It also gives you access to several functions for
manipulating gradients. You can select a gradient by clicking on
it in the list: it will then be shown in the
Brush/Pattern/Gradient area of the Toolbox. A few dozen nice
gradients come pre-installed with GIMP. You can create more using
the Gradient Editor.
General information about gradients and how they are used in GIMP
can be found in the Gradients
section.
The first four gradients are particular: they reproduce the gradient
between Foreground and background colors of toolbox in different ways.
The Gradients dialog is a dockable dialog; see the section on Dialogs and Docking for help on
manipulating it. It can be activated in several ways:
From the Toolbox menu:
File → Dialogs → Gradients.
From the Toolbox menu:
File → Dialogs → Create New Dock → Brushes, Patterns, and Gradients.
This gives you a dock containing three dialogs, with the
Gradients dialog one of them.
From the Toolbox, by clicking on the current gradient in the
Brush/Pattern/Gradient area.
From an image menu:
Dialogs → Gradients.
From the Tab menu in any dockable dialog:
Add Tab → Gradients.
From the image by using the G shortcut.
3.4.1. Grid/List modes
In the Tab menu, you can choose between View as
Grid and View as List.
In Grid mode, the gradients are laid out in a rectangular
array. They look quite dazzling when viewed this way, but it is
not very easy to pick the one you want, because of visual
interference from the neighboring ones. In List mode, the
more usable default, the gradients are lined up vertically, with
each row showing its name.
Note
In the Tab menu, the option Preview Size allows
you to adapt the size of gradient previews to your liking.
3.4.2. Using the Gradients dialog
The most basic, and most commonly used, operation with the
dialog is simply to click on one of the gradients in the
scrollable list, in order to make it GIMP's current gradient,
which will then be used by any operation that involves a
gradient.
If you double-click on a gradient, you open the
Gradient Editor where you will be able to edit its name. Note,
however, that you are only
allowed to change the names of gradients that you have created
yourself, not the ones that come pre-installed with GIMP. If
you try to rename a pre-installed gradient, you will be able to
edit the name, but as soon as you hit return or click somewhere
else, the name will revert to its original value. It is a
general rule that you cannot alter the resources that GIMP
pre-installs for you: brushes, patterns, gradients, etc; only
ones that you create yourself.
The buttons at the bottom of the dialog allow you to operate on
gradients in several ways:
This creates a new gradient, initialized as a simple
grayscale, and activates the Gradient Editor so that you
can alter it. Gradients that you create are automatically
saved in the gradients folder of your
personal GIMP directory, from which they are automatically
loaded when GIMP starts. (You can change this folder, or
add new ones, using the Preferences dialog.)
Duplicate Gradient
This creates a copy of the currently selected gradient.
You will be able to edit the copy even if you cannot edit
the original.
Delete Gradient
This removes all traces of the gradient, if you have
permission to do so. It asks for confirmation before
doing anything.
Refresh Gradients
If you add gradients to your personal
gradients folder by some means
other than this dialog, this button
causes the list to be reloaded, so that the new entries
will be available.
The functions performed by these buttons can also be accessed
from the dialog pop-up menu, activated by right-clicking
anywhere in the gradient list. The menu also gives you one
additional function:
Save as POV-Ray...
This allows you to save the gradient in the format used by
the POV-Ray 3D ray-tracing
program.
3.4.3.
Gradient Editor
Revision History
Revision $Revision: 1.12 $
2006-03-02
j.h
Figure 9.28.
The gradient editor
The Gradient Editor allows you to edit the colors in a
gradient. It can only be used on gradients you have created
yourself (or on a copy of a system gradient), not on system gradients
that come pre-installed with GIMP. This is a sophisticated tool that may
take a bit of effort to understand. The concept behind it is that a
gradient can be decomposed into a series of adjoining
segments, with each segment consisting of a
smooth transition from the color on the left edge to the color
on the right edge. The Gradient Editor allows you to pack
together any number of segments, with any colors you want for the
left and right edges of each segment, and with several options for
the shape of the transition from left to right.
How to Activate the Gradient Editor
You can activate the Gradient Editor in several ways:
By double-clicking on the gradient stripe in the Gradient
dialog.
From the context menu you get by right clicking on the
selected gradient name.
By clicking on the Edit gradient
button in the Gradient Dialog.
From the Gradient Menu you get by clicking on the small
triangle representing the Tab Menu in the Gradient Dialog.
Display
Name
In the name area, you have the tab menu button (the small triangle)
which opens a menu where you find the Gradient Editor Menu.
Gradient Display
Below the name, you see the current result of your work if the
Instant update option is checked; else,
changes will appear only when you release the mouse button.
If you simply move the mouse pointer on this display, it works
somewhat as a color-picker. Values of the pointed pixel are
displayed in a rather odd way. Position is
a number given to 3 decimal places, from 0.000 on the left to
1.000 on the right of the whole gradient. RGB,
HSV, Intensity and Opacity are also a ratio...
If you click-n-drag on display, then only position and RGB data
are displayed. But they are passed on to the Foreground color in
Toolbox and to the four first gradients of the palette.
Range Selection/Control Sliders
Below the gradient display, you see a set of black and
white triangles lined up in row. A
segment is the space between two
consecutive black triangles. Inside
each segment is a white triangle, which is used to
“warp”
the colors in the segment, in the same way that the middle
slider in the Levels tool warps the colors there. You can
select a segment by clicking between the two black triangles
that define it. You can select a range of segments
by shift-clicking on them. The selected range always
consists of a set of consecutive
segments, so if you skip over any when shift-clicking, they
will be included automatically.
If “Instant update” is checked, the display is updated
immediately after any slider movement; if it is unchecked,
updates only occur when you release the mouse button.
You can move sliders, segments and selections.If you
simply click-n-drag a slider, you only move
the corresponding transition. By Click-n-drag on a
segment you can move this segment up to the next
triangle. By Shift+click-n-drag on a segment/selection
, you can move this segment/selection and compress/
dilate next segments.
Scrollbar
Below the sliders is a scrollbar. This only comes into play if
you zoom in using the buttons at the bottom.
Feedback Area
Below the sliders is an area that initially is blank, but
depending on your actions, helpful hints or feedback
messages may appear here.
Buttons
At the bottom of the dialog appear five buttons:
Save.
Clicking this button causes the gradient, in its current
state, to be saved in your personal
gradients folder, so that it will
automatically be loaded the next time you start GIMP.
Revert.
Clicking this button undoes all of your editing. (However,
at the time this is being written, this function is not yet
implemented.)
Zoom Out.
Clicking this button shrinks the gradient display
horizontally.
Zoom In.
Clicking this button expands the gradient display
horizontally. You can then use the scrollbar to pan the
display left or right.
Zoom All.
Clicking this button resizes the display horizontally so that
it fits precisely into the window.
Gradient Editor Menu
Figure 9.29.
The Gradient Editor menu
You can access the Gradient Editor menu either by
right-clicking on the gradient display, or by choosing the top
item in the dialog's tab menu. The menu allows you to set the
left and right edge colors for each segment, and control the
transition from one color to the other.
Options
Left [Right] Endpoint's Color
These options allow you to choose a color for the
respective endpoint using a Color Editor.
Load Left [Right] Color From
Figure 9.30.
The "Load Color From" submenu
These options give you a number of alternative ways of
assigning colors to the endpoints. From the submenu you
can choose (assuming we're dealing with the left
endpoint):
Left Neighbor's Right Endpoint.
This choice will cause the color of the right endpoint
of the segment neighboring on the left to be assigned
to the left endpoint of the selected range.
Right Endpoint.
This choice will cause the color of the right endpoint
of the selected range to be assigned to the left
endpoint.
FG/BG color.
These choice cause GIMP's current foreground or
background color, as shown in the Toolbox, to be
assigned to the endpoint.
RGBA slots.
At the bottom of the menu are 10 "memory slots". You
can assign colors to them using the "Save" menu option
described below. If you choose one of the slots, the
color in it will be assigned to the endpoint.
Save Left [Right] Color To
These options cause the color of the endpoint in
question to be assigned to the "memory slot" selected
from the submenu.
Blending Function for Segment/Selection
Figure 9.31.
The Blending Function submenu
This option determines the course of the transition from
one endpoint of the range (segment or selection) to the other,
by fitting the specified type of function to the endpoints
and midpoint of the range:
Linear: Default option. Color varies
linearly from one endpoint of the range to the other.
Curved: Gradient varies more quickly on
ends of the range than on its middle.
Sinusoidal: The opposite of the curved
type. Gradients varies more quickly on center of the range than
on its ends.
Spherical (increasing): Gradient varies
more quickly on the left of the range than on its right.
Spherical (decreasing): Gradient varies
more quickly on the right than on the left.
Coloring Type for Segment/Selection
Figure 9.32.
The Coloring Type submenu
This option gives you additional control of the type of
transition from one endpoint to the other: as a line
either in RGB space or in HSV space.
Flip Segment/Selection
This option does a right-to-left flip of the selected
range (segment or selection), flipping all colors and endpoint
locations.
Replicate SEgment/Selection
This option splits the selected range (segment or selection)
into two parts, each of which is a perfect compressed copy of
the original range.
Split Segments at Midpoints
This option splits each segment in the selected range in into
two segments, splitting at the location of the white
triangle.
Split Segments Uniformly
This option is similar to the previous one, but it
splits each segment halfway between the endpoints,
instead of at the white triangle.
Delete Selection
This option deletes all segments in the selected range, (segment
or selection)replacing them with a single black triangle at the
center, and enlarging the segments on both sides to fill
the void.
Re-center Segment's midpoint/Selection midpoints
This option moves the white triangle for each segment in
the selected range to a point halfway between the
neighboring black triangles.
Re-distribute Handles in Segment/Selection
This option causes the black and white triangles in
the selected range to be shifted so that the distances
from one to the next are all equal.
Cette option déplace tous les triangles de l'intervalle
sélectionné pour les mettre à égale distance les uns des autres.
Blend Endpoints' Colors
This option is only available if more than one segment
is selected. It causes the colors at interior endpoints
in the range to be averaged, so that the transition
from each segment to the next is smooth.
Blend Endpoints' Opacity
This option does the same thing as the previous option,
but with opacity instead of color.
Caution
There is no "undo" available within the Gradient Editor, so be
careful!
![[Note]](../images/note.png)
![[Caution]](../images/caution.png)